Pressure on summit leaders as warming accelerates

Politicians must ensure that emission levels are reduced sufficiently to keep temperatures at no more than 2C above pre-industrial levels. [EPA]

The Paris climate conference (COP21) begins on November 30, bringing together the leaders of more than 190 nations.

Current commitments on greenhouse gas emissions, which cause global warming, run out in 2020. So this meeting, and any agreement reached, is likely to decide the future of our climate for decades to come.

The importance of reaching an agreement, which is both binding and meaningful, has been highlighted by the latest data from NASA’s National Centers for Environmental Information.

October 2015 was the Earth's warmest month since 1880. It beat the record set in September.

Out of the 1,630 months - 135 years - for which detailed records are available, six out of the seven warmest months have been in 2015. Only January 2007 breaks 2015's monopoly on record-breaking warmth.

The ongoing El Nino has undoubtedly contributed to these records. Typically, an El Nino adds about 0.1C to global temperatures. But El Ninos occur every three to five years, so it would be wrong to attribute the current warming to this natural event alone. The monthly departure from the long-term average temperature has been at least 0.87C since June.

It will be incumbent upon the politicians to ensure that emission levels are reduced sufficiently to keep temperatures at no more than 2C above pre-industrial levels. Climate scientists consider this to be the threshold above which warming will be both irreversible and catastrophic.

The enormity of the task is illustrated by the fact that current trajectories suggest a rise of as much as 5C by 2100. On the face of it those living in temperate latitudes may not think such a change to be particular alarming. Yet 5C is the difference between our current climate and the end of the last Ice Age, 20,000 years ago.

As always, vested interests will play their part in any agreement. Many of the world’s largest polluters also happen to be those with the greatest political power, and they will be reluctant to agree to anything which might be seen to compromise their industrial might.